It is well known to perform an angioplasty procedure to open an arterial vessel that is occluded due to arteriosclerosis, for example. Typically, a balloon catheter is inserted into the patient's arterial network and manipulated to the occluded region of the vessel which is generally proximate the heart. The balloon portion of the catheter is inflated so as to compress the arterial plaque against the vessel walls. The luminal area of the vessel is thereby increased which allows more blood to flow through the vessel.
While the angioplasty procedure may initially be successful, a significant percentage of patients experience restenosis of the treated area. That is, the opened region of the vessel gradually recloses in a relatively short amount of time, such as about six months. Although the exact mechanism is not understood, restenosis is generally believed to involve platelet aggregation, thrombus formation, and smooth cell migration and proliferation, either singly or in combination. However it occurs, restenosis ultimately negates the benefits achieved by the angioplasty procedure.
In order to prevent mechanical recoil of the vessel wall where the balloon is inflated, as well as to mitigate the effects of restenosis, a stent may be implanted in the opened region of the vessel after the angioplasty procedure. As known to one of ordinary skill in the art, a typical stent has a generally cylindrical shape to conform to the vessel and can be formed from a wire mesh. However, stents may irritate the vessel wall. Further, in some patients stents are believed to be the cause of rapid tissue growth, or intimal hyperplasia, through openings in the stent walls.
It would, therefore, be desirable to provide a technique to inhibit restenosis of a vessel region treated with a balloon catheter.